A MIDI controller provides a microcontroller that generates and transmits electronic signals to a music synthesizer in accordance with the MIDI protocol. A MIDI controller may be controlled by a human interface component that emulates the form of a traditional musical instrument. While MIDI controllers may have interfaces emulating a variety of instruments, most commonly, a MIDI controller is controlled by a keyboard interface, providing a MIDI keyboard controller, a well-known class of electronic musical instrument.
The microcontroller component of a MIDI keyboard controller is generally designed for a keyboard interface with a predetermined number of keys. As a result, the circuit design and wiring of a conventional MIDI controller is designed to provide a number of microcontroller inputs for wiring to a particular number of keys.
It is also known that keyboard instruments may have other human interfaces aside from a keyboard. For example, a drawbar-type electric organ is a type of keyboard instrument incorporating a set of drawbars that may be operated to control sounds generated electromagnetically by a set of tonewheels. Sound generated by a drawbar-type organ is formed by additive synthesis, and is made up of the sum of a number of component waveforms. Each component waveform is generally referred to as a partial. Each note played by the organ is a sum of nine different, integer-related partials, called harmonics.
A user of a drawbar-type organ may control the waveform composition of sound generated by the organ by setting each drawbar of the organ into different configurations. Each drawbar corresponds to a particular harmonic, a sinusoidal waveform having a particular frequency proportional to the teeth of a tonewheel. The position of the drawbar, generally ranging over nine positions from fully extended to fully depressed, corresponds to the volume of that harmonic, amplified by an amplifier circuit of the organ. The positions of a drawbar range from a 0 position, where a corresponding harmonic is silent, to an 8 position, where a corresponding harmonic is at full volume.
Drawbar-type organs were produced by the Hammond Instrument Company in different models that may have up to 146 keys and variable numbers of drawbars. Keys may be arranged in rows, also referred to as manuals. Each manual may be controlled by one or more sets of drawbars. Therefore, the notes of one manual can have vastly different timbres than those of another depending on how the drawbars are configured. Drawbar-type organs may further include a one-octave or a two-octave set of foot pedals to produce lower bass tones, which may be controlled by additional drawbars. The many models of drawbar-type organs that were produced provided these elements in a variety of quantities and configurations.
Among musical instruments, drawbars are only found on drawbar-type organs or on some electronic keyboard instruments that emulate the sound of tonewheels found on such organs. While several companies produce electronic keyboard instruments emulating drawbar-type organs, and some such instruments incorporate drawbars as an interface, each such instrument only provides for a fixed configuration having a set number of keyboards and drawbars.
There has not been a MIDI controller design that may be wired to a variety of human interfaces corresponding to the many models of drawbar-type organs produced, each having different quantities and configurations of keys and drawbars.